Method of handling busy calls in a multiple zone communication system

Abstract

A method of handling busy calls, performed by a controlling entity (ZC1) in a multiple-zone system, includes the steps of issuing (201) a request to participate in a call to one or more participating zones (101, 103, and 105) and concluding (203) that at least one zone of the participating zones (101, 103, and 105) is unable to grant the call, thereby resulting in a busy status for the call. The controlling entity (ZC1) informs the participating zones (101, 103 and 105) of the busy status. A resource available notification is received (209) from a first zone, and the controlling entity (ZC1) determines (211) if a predetermined number of the participating zones (101, 103, and 105) have indicated ability to grant the call. When at least one zone of the one or more participating zones has not indicated ability to grant the call, the controlling entity (ZC1) issues (213) a still busy notification to the first zone, which still busy notification indicates that the call still has a busy status.

What is claimed is: 
     
       1. A method comprising the steps of: issuing a request to participate in a call to one or more participating zones of a plurality of zones in a communication system, wherein each of the plurality of zones is comprised of a plurality of communication sites;   concluding that at least one zone of the one or more participating zones is unable to grant the call, thereby resulting in a busy status for the call;   informing the one or more participating zones of the busy status;   obtaining, by a first zone of the one or more participating zones, at least one communication resource necessary to grant the call;   issuing, by the first zone, a resource available notification;   receiving the resource available notification from the first zone;   determining if a first predetermined number of the one or more participating zones have indicated ability to grant the call;   when a second predetermined number of the one or more participating zones has not indicated ability to grant the call, issuing a still busy notification to the first zone, which still busy notification indicates that the call still has a busy status;   upon receiving the still busy notification, returning, by the first zone, the at least one communication resource for possible allocation to another call.   
     
     
       2. The method of claim 1, further comprising the step of, upon receipt of the still busy notification, inhibiting, by the first zone, performing the steps of: obtaining any further communication resources necessary to grant the call; and   issuing any further resource available notifications.   
     
     
       3. The method of claim 1, further comprising the step of, when a third predetermined number of the one or more participating zones have indicated ability to grant the call, issuing another request to participate in the call to the one or more participating zones, wherein the third predetermined number is within three of the first predetermined number. 
     
     
       4. The method of claim 3, further comprising the step of repeating the concluding, informing, obtaining, issuing a resource available notification, receiving, determining, and issuing another request to participate steps until the first predetermined number of the one or more participating zones is able to grant the call. 
     
     
       5. The method of claim 1, wherein the step of concluding comprises the step of receiving an indication from at least one of the one or more participating zones, which indication indicates whether or not the zone is able to allocate at least one communication resource necessary to grant the call. 
     
     
       6. The method of claim 1, wherein the step of concluding comprises the step of determining if a controlling zone is able to allocate at least one communication resource necessary to grant the call. 
     
     
       7. The method of claim 1, wherein the step of concluding comprises the step of receiving an indication from at least one of the one or more participating zones, which indication indicates whether or not the call should proceed. 
     
     
       8. The method of claim 1, wherein the steps of issuing a request to participate, concluding, informing, receiving, determining, and issuing a still busy notification are performed by a controlling zone controller. 
     
     
       9. The method of claim 1, wherein the first predetermined number is all of the one or more participating zones and the second predetermined number is one of the one or more participating zones. 
     
     
       10. A method performed by a controlling entity in a system comprising a plurality of zones, the method comprising the steps of: issuing a request to participate in a call to one or more participating zones of the plurality of zones, wherein each of the plurality of zones is comprised of a plurality of communication sites;   concluding that at least one zone of the one or more participating zones is unable to grant the call, thereby resulting in a busy status for the call;   informing the one or more participating zones of the busy status;   receiving a resource available notification from a first zone;   determining if a first predetermined number of the one or more participating zones have indicated ability to grant the call;   when a second predetermined number of the one or more participating zones has not indicated ability to grant the call, issuing a still busy notification to the first zone, which still busy notification indicates that the call still has a busy status.   
     
     
       11. The method of claim 10, further comprising the step of when a third predetermined number of the one or more participating zones have indicated ability to grant the call, issuing another request to participate in a call to one or more participating zones of the plurality of zones, wherein the third predetermined number is within three of the first predetermined number. 
     
     
       12. The method of claim 11, further comprising the step of repeating the concluding, informing, receiving, determining, and issuing another request to participate steps until the first predetermined number of the one or more participating zones is able to grant the call. 
     
     
       13. The method of claim 10, wherein the step of concluding comprises the step of receiving an indication from at least one of the one or more participating zones, which indication indicates whether or not the zone is able to allocate at least one communication resource necessary to grant the call. 
     
     
       14. The method of claim 10, wherein the step of concluding comprises the step of determining if a controlling zone is able to allocate at least one communication resource necessary to grant the call. 
     
     
       15. The method of claim 10, wherein the step of concluding comprises the step of receiving an indication from at least one of the one or more participating zones, which indication indicates whether or not the call should proceed. 
     
     
       16. The method of claim 10, wherein the controlling entity is a controlling zone controller. 
     
     
       17. The method of claim 10, wherein the first predetermined number is all of the one or more participating zones and the second predetermined number is one of the one or more participating zones. 
     
     
       18. A method performed by a participating zone controller in a system comprising a plurality of zones, wherein each of the plurality of zones is comprised of a plurality of communication sites the method comprising the steps of: receiving a request to participate in a call;   entering the call in a busy queue when the participating zone controller is unable to grant at least one communication resource necessary to grant the call;   subsequently obtaining at least one communication resource necessary to grant the call;   issuing a resource available notification;   when a still busy notification is received, returning the at least one communication resource for possible allocation to another call.   
     
     
       19. The method of claim 18, further comprising the step of, upon receipt of the still busy notification, inhibiting, by the participating zone controller, performing the steps of: obtaining any further communication resources necessary to grant the call; and   issuing any further resource available notifications.   
     
     
       20. The method of claim 18, further comprising the step of receiving, from a controlling zone controller, a busy status notification indicating that the call is busy in one or more participating zones of the plurality of zones.